Exoplanet find Breaking new ground in the detection of planets beyond our solar system, European astronomers have recorded the most lightweight world to be discovered so far through direct observation.

Hundreds of extra-solar planets have been found since 1995, but almost all of them have been discovered through inference -- by the way their gravitational pull affects their star's light or the star itself.

The new discovery is a gas giant about four to five times the mass of Jupiter, the largest planet of our solar system, say astronomers at the European Southern Observatory (ESO).

It orbits a young star, HD 95086, at around 56 times the distance between the Earth and the Sun.

"Only a few planets have been directly observed so far, making every single discovery an important milestone on the road to understanding giant planets and how they form."

A total of 720 extrasolar planets have been found since the first was spotted in 1995. Another 2,595 findings by the specialist Kepler orbital telescope await confirmation.

All but a dozen have been detected indirectly, either through alterations in starlight or through a wobble in a star's motion, caused by the gravitational tug of a passing planet as it swings by.

The new sighting, called HD 95086b, has the lowest mass of any directly observed exoplanet, say the astronomers.

"The less mass that a planet has, the harder it is to observe it," explains another team member Anne-Marie Lagrange also from IPAG.

Astronomers used an adaptive optics instrument which removes blur caused by Earth's atmosphere mounted on one of the gigantic 8.2-metre units at ESO's Very Large Telescope (VLT) in Chile's Atacama desert.

The observations were made using infrared light and a technique called differential imaging, which improves the image contrast between the planet and host star.

So far, no exoplanet spotted has the potential to be a home away from home -- a rocky planet that orbits in a balmy zone, enabling water to exist in liquid form and thus nurture life as we know it.

The new study is to be published in the Astrophysical Journal Letters.